Spent a quarter on our SKAN 4 setup. Do we have to redo it all for AdAttributionKit?

Mostly no. AdAttributionKit, introduced at WWDC 2024, keeps SKAN 4's privacy model: three timed postbacks, fine and coarse conversion values, crowd anonymity tiers and randomised delays. Your SKAN 4 schema is the starting point, not a rebuild. What changes: AAK measures re-engagement for click-based interactions, routing installed users through a universal link while the interaction is attributed, which SKAN could not do. It covers alternative app marketplaces as well as the App Store, supports more creative formats, and adds a developer mode that removes timing randomisation, so you can validate a setup in minutes rather than days. The two frameworks interoperate, so run both while your networks and install base move across. Your MMP should ingest both sets of postbacks into one view; Linkrunner's SKAN tooling carries both frameworks. Primer if useful: https://linkrunner.io/blog/what-is-adattributionkit-apple-skan-successor